Hydro-pneumatic pressure control apparatus



Get. 9, 1956 H. T. DINKELKAMP 2,765,804

HYDRO-PNEUMATIC PRESSURE CONTROL APPARATUS Filed Jan. 22, 1953 HYDRO-PNEUMATIC PRESSURE CONTROL APPARATUS Henry T. Dinkelkamp, Niles, lll., assigner to Stewart- Warner Corporation, Chicago, lll., a corporation of Virginia Application January 22, 1953, Serial No. 332,743

2 Claims. (Cl. 137-95) The invention relates generally to pressure control apparatus, and more particularly to means for preventing the production of excessive pressure at the outlet of a pneumatically operated pump for lubricants and other uids.

When grease, oil, or other materials are pumped by a compressed air operated motor and supplied to a bearing, or into a container, through a manually operable control valve, there is danger that variations in the pressure at which the compressed air is supplied to the air motor will result in excessive variations in the pressure in the conduit connecting the pump to the control valve. Such excessive pressure may cause bursting of the conduit or damage to the control valve or the part to which the material is being supplied.

It is therefore the primary object of the invention to provide a control valve which will accurately limit the pressure developed at the outlet of the pump.

Another object is to provide a pressure regulating control valve for the supply of air to an air motor, which is operated in response to the pressure of the material at the discharge of a pump driven by the air motor, in which means are provided to prevent the build-up of excessive pressures at the outlet of the pump even though the pressure regulating control valve does not seat properly.

Other objects will appear from the following description, reference being had to the accompanying drawing which shows a lubricant pump and air motor for driving the same in more or less schematic section, a pressure regulating control valve in central vertical section, and a manually operable material ilow control valve `in perspective.

The compressed air operated material pump is diagrammatically illustrated as of the type which may have a portion thereof inserted within a shipping drum and be supported thereby to remove the contents thereof. For the purposes of this application, it will be assumed that the material handled is a lubricant.

The pump comprises a cylinder having a foot valve 12 cooperating with the foot valve seat 14 and suitably restrained against more than limited movement from its seat. A piston 16 is reciprocable in the cylinder and is secured to a piston rod 18 by means of a suitable cage structure 20 enclosing a check valve 22. The piston rod 18 is secured to or integral with an air motor piston ro-d 24 extending through a suitable packing gland 26 into a cylinder 2S. A suitable piston 30 is secured to the upper end of the rod 24. At the upper end of the body 32, which provides the cylinder 23, there is a valve housing 34 providing a valve chamber 36 in which a D slide valve is reciprocable. Valve 40 is operated by a stem 41 which, as shown in the prior patent to E. W. Davis, No. 2,556,680, is suitably shifted upwardly to the position shown in dotted lines near the upper end of the stroke of the piston 30, and shifted downwardly as the piston approaches the end of its downward stroke. When in the lower position, shown in full lines, the valve connects passageway 42 leading to the upper end of the cylinder 30 to the atmosphere through an exhaust port 44. Air tlowing into the chamber 36 through a supply conduit 46 tlows from the chamber 36 to the lower end of cylinder 28 through a conduit 48. In its upper position, the valve 40 permits air under pressure to flow to the upper end of the cylinder and permits exhaust of the cylinder in the customary manner.

The lubricant discharged from the pump flows through a conduit 50 to a T 52 and thence through a flexible hose 54 to a manually operable control valve 56, the latter having a discharge pipe 58 which may be provided with a suitable coupling device 61 at its free end.

ln order to assure that the hose 54 and other parts of the system, and the parts supplied with lubricant thereby, are not subjected to excessive pressure, an adjustable air pressure regulating device has been provided which is effective to prevent the lubricant pressure at the discharge of the pump to exceed a valve predetermined by the adjustment of the valve. This pressure regulating device comprises a body 60 provided with a central bore 62, a counterbore 64 in which a centrally open control valve seat 65 has a press tit, and a valve chamber 66. A movable control valve 68 is cooperable with the valve seat 65 and has a stem 70 reciprocable in a bore 72 formed in a valve stem guide 74 which is threaded at the lower end of the chamber 66, the `valve stem being provided with an O-ring seal 76. The lower end of the bore 72 is enlarged to provide a shoulder against which a plunger guide S0 is pressed by a fitting 82 threaded in the lower end of the valve stem guide 74. A plunger 84 is reciprocable in the guide S0 and is surrounded by suitable packing 36 which is located between the lower surface of the guide and a washerlike supporting plate S8. rl`he lower end of guide '74 is connected to the T 52 by a centrally bored fitting 82, having a counterbore 92 in the upper end of the iitting which deiines with the packing 86 and the movable plunger 84 a pressure chamber 90 isolated from communication with either the upstream or downstream side of the air pressure control valve 68 and connected through the tting 82 to pump outlet pressure in the T S2.

The valve 68 is biased to'rnove to open position by two coil springs 94 and 495 which are compressed between spring saddles 96 and 97 within a hollow cap 98 threaded in the upper end of the body 60 and held in adjusted position 'by a lock nut 100. This cap is provided with an air escape opening 102. The spring saddle 96 has a central projection 104 which bears in a cooperating depression formed in thev center of the top of the cap 98, while the lower spring saddle 97 hasa central conical depression 'for centering engagement -with a steel ball 106 which, in turn, is centered in a conical recess in the upper end of valvestem 108. The ball 106 forms an exhaust valve adapted to bear against an exhaust valve seat 107 encircling the open upper end of the bore 62. The valve stem 108 slides freely in the bore 62. The stem 108 is made slightly smaller than the bore 62 to provide a small unsealed clearance or vent along the bore for bleeding a small flow of air under pressure from the downstream side of the valve seat 65 out through the port 102 whenever the ball valve 106 is not seated. The lower portion 109 of the stern 108 is of reduced diameter and has an enlarged head 110 and extensions thereof which press against the valve stem 70 and hold the valve disc 63 in position on the stem.

Air under pressure from a source 111 is supplied to the valve chamber 66 through a conduit 112 and a shutott valve 120, and is discharged from the valve body through a port 114 and conduit 46.

The restricted bleed passage to the atmosphere formed by the slight clearance between the valve stem 108 and the bore 62 provides assurance that even if there were some slight leakage when the valve 68 is in its closed position, the pressure of the compressed air supplied to the pump would not gradually rise to an excessive pressure with resultant excessive pressures in the lubricant discharge conduits, and, what is more important, protection against the development of excessive pressure at the bearing or other part to which lubricant is supplied. The air which leaks past the valve stem 108 can Vescape to -the atmosphere through the small opening 192 in the cap S. However, such leakage is prevented when the valve 68 is in fully open position, the position in which it is shown, by virtue of the fact that the ball valve 106 is seated. The stem S extending between the control valve 68 and the exhaust valve 106 is dirnensioned to coordinate movement of the two valves so that upon seating of either valve the other valve is moved away from its seat to open position. To preclude thepossibility of the accumulation of lubricant in the bore 72 beneath valve stem 70,due to unexpected leakage past the plunger 84, this space may be provided with a minute Vent to the atmosphere.

In operation, the source of compressed air is turned on by opening valve 129 and, assuming that there `is-no substantial pressure at the discharge of the lubricant pump, the springs g4, 9S will hold the valve 68 away from its seat, and air will ow past this valve through the conduit 46 tothe valve chamber 36 of the reciprocable air motor. The latter will commence operating and raise the pressure on the discharge side of the pump. Assuming that the manuallyoperable control valve S6 vis closed, the pressure in the chamber 99 will build up until the pressure operating against the lower end of the plunger 84 is sufhcient to expand the chamber 9i) by moving plunger 34 upwardly. The plunger 84 moves the valve 68 vand its associated parts upwardly against the combined force of thesprings 94 and 95 to seat the valve 68.

It the valve 68 does not form a perfect airtight seal with its seat 65, resulting leakage of air would, if there were no slight clearance between the stem 163 and its bore 62, tend gradually to raise the pressure applied to one of 'the aces of the air motor piston 30, and thereby increase the grease pressure to an excessive extent. It is thus of .some considerable importance that this slight clearance be provided, although obviously it should not be suicient to result in unnecessarily wasteful escape of compressed air.

As soon las the manual control v-alve 56 is operated to permit discharge of grease to the bearing or other part to be supplied with lubricant, the lubricant pressure eilective against the lower end of the stem 84 will drop, permitting thersprings 94, 95 to force the valve 68 from its seat and again permit air to ow to the air motor. 'In this connection it should be noted that the operation Yof the hydropneumatic pressure control valve is independent of the pressure of the compressed air, because the diameters of the bores 62 and 72 are the same. The effective diameter of the valve seat 65 is also the same as that of the valve stem 70 and Vsubstantiallypthe same as that of valve stem V108. As a result, the only forces acting to move `the valve 68 are those due to the lubricant pressu-re at the lowerl end of the plunger 84 and the force due to the compression of the coil springs 94, 95. When the manually operated control valve 56 is permitted to close, the lubricant pressure will again risel to the value preset by the degree of compression of springs 94 and 95, whereupon the v-alve 68 will again be forced to closed position.

While I have shown and described a preferred embodiment of my invention, it will be apparent that numerous variations and modifications thereof Vmay be made without departing from the underlying principles of the invention. I therefore desire, by the following claims, to include withinthe'scope of the invention all such variations and modifications by which subtantially the results of my invention may be obtained through the use of substantially the same or equivalent means.

I claim:

l. Apparatus for controlling and limiting the effective supply and pressure of one liuid medium in response to the pressure of another fluid medium, comprising, in combination, means defining a control valve opening, a control valve mounted for movement between anopen position and a closed position in relation to said control valve opening, means defining a fluid inlet connection tothe upstream side of said control valveopening for a lfirstiiuid medium, means deiining a fluid outlet connection fromthe downstream side of said control valve opening for the first iiuid medium, means deiining an exhaust valve opening, means forming a bleed passage of very small effective iiow area extending from the downstream side of said control valve opening to exhaust through said exhaust valve opening, an exhaust valve mounted for movement between an open position and a closed position in relation to said exhaust valve opening, valve coordinating means connected to said control valve and to said exhaust valve and dimensioned to effect movement of said exhaust valve to open position upon movement of said control valve into closed position and to effect movement of said exhaust valve to closed position upon movement of said control Vvalve to open position, means defining an expandable chamber adapted to receive a second iiuid medium under pressure and including means movable in opposite directions upon expansion and contraction of the chamber, means isolating said chamber from communication with both the upstream and the downstream sides of said control valve opening, resilient means associated with said chamber defining means to yieldably urge contraction of said chamber, and means connecting said movable chamber defining means to said control valve to effect upon predetermined expansion of said chamber closing of said control valve and through operation of said coordinating means opening of said exhaust valve and to effect upon predetermined contraction of said chamber opening of said control valve and through operation of said coordinating means closing of said exhaust valve.

2. Apparatus for controlling the supply of compressed air to a pneumatically operated pump in response to the discharged pressure of the pump, comprising, in combination, valve body means defining an inlet and an outlet for compressed air, means forming a control valve seat defining an opening between said inlet and said outlet, a control valve separably engageable with the upstream side of said seat to close off said inlet from said outlet,^rst and second guide stems extending from the upstream and downstream sides respectively of said control valve, said valve body ymeans deiining -two -bores therein .receiving said respective stems for translation vtherein,-means-forrn ing beyond the end of said rst stema chamber adapted to be connected with a pump outlet, means isolating said chamber from communication with said control valve, a plunger extending reciprocably into said chamber and having one end exposed to the-interiorithereof and .the other end opposing the adjacent end of said iirst 'stem `to apply force thereto in accordance with the iluid pressure within said chamber, said valvehody bore-receiving-said second stem opening outwardly to the atmosphere from the outlet `side of said control valve seat, vsaid second -stem being dimensioned transversely in relation to said last mentioned bore to form therewith Va bleed passage of very small eiective flow area between the downstream side of said valve seat and the atmosphere, means deiining an exhaust vdve seat encircling the outer end of said last mentioned bore, a spherical member engagingV the outer end of said second stem and dirnensioned to form an exhaust valve separably engageable with said exhaust valve seat to close said bleed passage, a compression spring mounted tourge said exhaust valve into engagement with 5 the exhaust valve seat therefor, and said second valve stem being dimensioned to force said exhaust valve away from the seat therefor upon movement of said control valve into engagement with the seat thereof by said pressure actuated plunger and to force said control valve away from the seat therefor upon engagement of said exhaust valve with said seat therefor by said compression spring.

References Cited in the le of this patent UNITED STATES PATENTS Baldwin Dec. 2, 1902 Fulton Dec. 30, 1902 Blanchard et a1. Jan. 2, 1917 Page u Feb. 11, 1919 Grith July 29, 1941 Stark Dec. 23, 1952 

